Gyratory grinder



Sepf. 12, 1967 E. STETTINIUS GYRATORY GRINDER 2 Sheets-Sheet 1 Filed Aug. 16, 1965 FIG. 1

INVENTOR. KENNETH E. STETTINIUS ATTORNEYS Sept. 12, 1967 E. STETTINiUS 3,341,135

GYRATORY GRINDER Filed Aug. 16, 1965 2 Sheets-Sheet 2 INVENTOR.

KENNETH E. STETTINIUS ATTORNEYS United States Patent 3,341,136 GYRATORY GRINDER Kenneth E. Stetfinius, Le Roy, N.Y., assignor to Lapp Insulator Co., Inc., Le Roy, N.Y., a corporation of New York Filed Aug. 16, 1965, Ser. No. 480,043 17 Claims. (Cl. 241-172) The present invention relates to gyratory grinders or mills and more particularly to mills driven in a horizontal gyratory motion and containing a charge of pebbles 'or balls which grind material by impact and attrition.

At present, two basic types of ball mills are known, tumbling ball mills that generally rotate about a horizontal axis and gyratory mills. Each contains a charge of impact objects referred to throughout the specification and claims interchangeably as either pebbles or balls. Such impact objects can be any of a variety of sizes, shapes and masses depending upon the mill in which they are used and the material which they are grinding. In tumbling ball mills, the balls must be of relatively large mass because they are. raised up and allowed to cascade downward over one another and accomplish grinding by impact from the force of their fall. In gyratory mills, the grinding chamber is normally in the shape of an annulus, the pebble size of the pebble charge is generally smaller, and the pebbles are jiggled by a gyratory motion in a horizontal plane which causes the pebbles to tend to congregate around the periphery of the mill, rising at the outside of the chamber, spilling over the top toward the inside and traveling outw'ard again. Grinding in such a device is accomplished by milling about and rubbing together of the shaken pebbles.

It is an object of this invention to increase the speed, capacity, and eificiency of a gyratory ball mill. I

Another object of the invention is to grind materials, either wet or dry, to a finer and more uniform size more quickly and less expensively than was possible with previously known grinders.

These and other objects of the invention will be apparent hereinafter from the specification, the drawings, and from the subject matter claimed. Specific preferred embodiments of the invention will hereinafter be more fully described, the inventive subject matter being claimed at the end of this specification.

In the drawings:

FIG. 1.is a top view of one embodiment of an improved gyratory mill according to the present invention; 7 FIG. 2 is a side view, partly in section, of the improved gyratory mill of FIG. 1.

FIG. 3 is an end view, partly in section, of the improved gyratory mill of FIG. 1.

7 Generally, the improved gyratory grinder according to the invention has a'grinding chamber which can be any convenient shape and size and which is filled about one-half full with a charge of pebbles that are preferably relatively small for greater contact with each other. Instead of jiggling these pebbles about in the usual way, impact rods or bats are arranged to extend into the grinding chamber and move with the chamber for batting the pebbles about to impart great energy to them. In operation, the pebbles are knocked about such a chamber violently and substantially uniformly so that grinding is accomplished rapidly and continuously throughout substantially the entire volume of the chamber.

Patented Sept. 12, 1967 Referring to the drawings throughout which corresponding parts are given the same reference numerals, one' preferred embodiment of the inventive gyratory mill is formed with a generally rectangular grinding box 10 with an associated cover 11. Grinding chamber 10 can be any convenient size or shape, and the illustrated rectangular shape functions quit-e well. Grinding chamber 10 is supported for gyratory motion in any convenient manner, and in the illustrated mill, chamber 10 is supported on a cradle-like structure. This support structure includes a pair of elongated U-shaped cradle arms 12 (see FIGS. 2 and 3) which extend longitudinally underneath the box 10. A plurality of L-shaped side cradle pieces 14 are secured in pairs to the outer surface of each of the longitudinal cradle arms and are adapted to engage the sides of the box 10 adjacent each of its four corners. As shown in FIG. 2, each pair of side cradle pieces 14 has a plate member 15 secured horizontally therebetween and formed with a notch 16 into which the lower, enlarged end of a suitable cover toggle 17 is adapted to engage, for fastening the cover 11 securely onto the top of the grinding box 10.

As best shown in FIGS. 2 and 3, each of the corners of cradle-like frame preferably has a stabilizer rod 18 movably connected thereto in any suitable manner, for example, by the bolted brackets 19 attached to the, outermost side cradle members 14. The bottom ends of the stabilizer rods 18 are similarly connected to the respective corners of a rectangular support frame 20 as by bolted clamps 21. Stabilizer rods 18 are preferred for helping to maintain box 10 in uniform level orientation and for preventing any rotation as it is gyrated.

Gyratory motion is preferably imparted to grinding box 10 through the support cradle structure. In the illustrated embodiment, cradle members 12 are secured to drive plate member 22 which in turn is connected to drive mechanism 23 through an eccentric coupling 24 which translates shaft rotation into a horizontal orbital or gyratory motion. The path of a point traveling in such gyratory motion is illustrated by the broken-line arrows in FIG. 1. Drive means 23 is preferably variable 'speed from about 200 to 300 rpm. to adjust the grinding operation to various specific applications, but no specific speeds or gyr-ation sizes are essential to the invention.

Impact rods or bats 26, extending preferably vertically into grinding box 10, are preferably fastened to cover 11. Rods 26 can be secured to cover 11 in any convenient way, and two ways of securing rods 26 in place are shown in FIG. 3. Rods 26 can be made vertically adjustable within tubular projections 25 extending upwardly from the upper surface of cover 11. With such an arrangement, thumb screws 27 are threaded through projections 25 and engage rods 26 to secure them in place. Rods 26 can also be secured permanently in place on cover 11 by being cemented within individual housings 35 each of which is preferably removably secured to cover 11 by means such as bolts 36 and 37. Any of a variety of cements 38 such as lead alloy or portland cements can be used to secure a rod 26 within a housing 35, and new rods canreplace worn ones within removable housings 35.

With either method of securing rods 26 to cover 11, it is preferred that rods 26 be substantially uniformly spaced over the surface area of cover 11 so as to extend downward into grinding box 10 at uniform intervals throughout box 10. The spacing between adjacent rods 26 is preferably made substantially equal to the diameter of the gyratory motion of the grinding chamber as indicated by the dotted arrows in FIG. 1. The rods or bats 26 are preferably made of ceramic material and preferably extend to near the bottom of box 10. However, rods may also be made of cermet materials such as tungsten carbide and can extend all the way to the bottom of box 10.

Referring to FIG. 3, grinding box is preferably lined with a material for increasing its grinding efficiency. On the one hand, a resilient liner such as rubber can assist in keeping the pebbles flying violently about, and on the other hand, a hard liner can be used to accomplish some grinding in contacts between pebbles and the liner. In the illustrated embodiment, the side and bottom walls of box 10 are provided with a liner 31 preferably made of high density alumina ceramic material, and the underside of cover 11 is provided with a liner 33 of neoprene, rubber, or other resilient material. Liner 33, in the illustrated embodiment forms a gasket between cover 11 and outturned flange 32 of the side walls of box 10. Of course, other liner materials including other ceramic or cermet materials can be used, or liners can be omitted within the spirit of the invention.

Grinding box 10 is preferably about half filled with a charge of balls or pebbles 34 as shown in FIG. 3. Since the pebbles 34 are batted violently about by bats 26 and use kinetic energy thus acquired for their grinding force rather than relying upon their mass and the force of gravity, pebbles 34 are preferably of relatively small size so as to be more numerous and to have more frequent contact with each other resulting in a greater area of effective contact per unit of time in operation. Thus, one very successful grinder according to the invention has used ceramic pebbles of approximately one-quarter inch diameter and bats of approximately one inch diameter. Of course, pebbles of materials other than ceramic can be used, including metallic or cermet materials.

The inventive mill is adapted for continuous grinding of either wet or dry materials and continuous input and output of materials preferably through inlet duct 28 in cover 11 and output chute 29 at the opposite end of box 10 as best shown in FIG. 2. A perforated discharge grid 40 is preferably removably arranged over the output end of box 10 as shown in the sectioned portion of FIG. 2 to retain pebbles within the box. Perforations in the output grid 40 are preferably relatively large compared to the fineness of the ground product, and output grid 40 is preferably easily removable and replaceable to remedy plugged or worn perforations. Any worn pebbles passing through discharge grid 40 are preferably removed by a screening after the grinding operation.

In operation, grinding box 10 is driven in a relatively rapid circular horizontal gyratory motion preferablyof approximately 200 to 300 r.p.m. in an orbit such as indicated by the dotted arrows in FIG. 1. This imparts rapid circular motion to the rods 26 as well as box 10, and rods 26 thus repeatedly bat pebbles 34 violently about the inside of box 10. Pebbles 34 are driven substantially uniformly throughout the volume of box 10 with high speed and energy and collide with each other, the bats 26, and the inside surfaces of box 10 repeatedly and rapidly to grind material thoroughly and quickly.

Spacing of the bats 26 by a distance approximately equal to the diameter of the gyratory motion has been found to produce the desired violent agitation of the pebbles and very effective and improved grinding action. However, the invention is not limited to any particular spacing of bats, amplitude of gyratory motion, or size of grinding chamber.

Other features, advantages, and other specific embodiments of this invention will be apparent to those exercising ordinary skill in the pertinent art afterreading the foregoing disclosure. In this regard, while specific preferred embodiments of my invention have been described in considerable detail, such disclosure is intended in .an

illustrative, rather than a limiting sense, and other embodiments, variations, and modifications can be effected within the spirit of the invention and the scope of the subject matter as disclosed and claimed.

I claim:

1. In a gyratory ball mill having a grinding chamber containing a charge of grinding pebbles and drive means connected to said chamber for driving said chamber in a gyratory motion in a horizontal plane, the improvement comprising: a plurality of rod members extending rigidly within said chamber, said rods being spaced throughout said chamber and being movable with said chamber for repeatedly batting said pebbles about as said chamber is gyrated by said drive means.

2. The gyratory ball mill of claim 1 wherein said rod members are releasably secured to said grinding chamber and extend vertically therein.

3. The gyratory ball mill of claim 2 wherein said rod members are adjustable vertically within said chamber.

4. The gyratory ball mill of claim 1 wherein said chamber comprises substantially uninterrupted open space, and said rod members are spaced substantially uniformy throughout said chamber.

5. The gyratory ball mill of claim 4 wherein the diameter of said gyratory motion is substantially equal to the distance between adjacent ones of said plurality of rod members.

6. The gyratory ball mill of claim 1 wherein said pebbles and said rod members are formed of ceramic material.

7. The gyratory ball mill of claim 1 including means for continuously introducing material to be ground into said chamber and means for continuously removing ground material from said chamber.

8. In a gyratory ball mill driven in a horizontal gyratory motion, the combination comprising:

(a) a grinding box enclosing a volume substantially all of which is adapted for grinding;

(b) a charge of grinding pebbles disposed in said box;

(c) a cover fastened to said grinding box and configured to define a plurality of apertures spaced substantially uniformly over said cover; and

(d) a plurality of rods disposed in said apertures and extending rigidly downward into said volume for continually batting said pebbles about as said grinding box is gyrated.

9. The gyratory ball mill of claim 8 including means on said cover arranged for securing said rods removably in place.

10. The gyratory ball mill of claim 8 wherein said pebbles and said rods are formed of ceramic material.

11. The gyratory ball mill of claim 8 wherein the diameter of said gyratory motion is substantially equal to the distance between adjacent ones of said plurality of rods.

12. The gyratory ball mill of claim 8 including means for continuously introducing material to be ground into said chamber and means for continuously removing ground material from said chamber.

13. The gyratory ball mill of claim 8 wherein said cover member is releasably secured atop said grinding box.

14. A gyratory ball mill comprising:

(a) an open top, substantially rectangular grinding box;

(b) a charge of ceramic grinding pebbles disposed within said grinding box;

(c) a cover member adapted to be releasably secured atop said grinding box and having a plurality of apertures therethrough substantially uniformly spaced over the surface of said cover member;

(d) means for driving said box in a gyratory motion in a horizontal plane;

(e) a plurality of ceramic rods one of which is disposed in each of said apertures so as to extend rigidly downward into said grinding box, said rods being adapted for repeatedly batting said pebbles about as said grinding box is gyrated by said drive means; and

(f) means for removably securing said rods in place in said apertures.

15. The gyratory ball mill of claim 14 wherein said grinding box is lined with a ceramic material, and the bottom surface of said cover member is lined with a resilient material.

16. The gyratory ball mill of claim 14 wherein said diameter of said gyratory motion is substantially equal to the distance between adjacent ones of said plurality of rods.

17. The gyratory ball mill of claim 14 including means for continuously introducing material to be ground into said chamber and means for continuously removing ground material from said chamber.

References Cited UNITED STATES PATENTS 2,982,485 5/1961 Fahrenwald 241-171 3,015,451 1/1962 Goeser 241-172 3,100,088 8/1963 Podmore et a1. 241170 WILLIAM W. DYER, JR., Primary Examiner. GERALD A. DOST, Examiner. 

1. IN A GYRATORY BALL MILL HAVING A GRINDING CHAMBER CONTAINING A CHARGE OF GRINDING PEBBLES AND DRIVE MEANS CONNECTED TO SAID CHAMBER FOR DRIVING SAID CHAMBER IN A GYRATORY MOTION IN A HORIZONTAL PLANE, THE IMPROVEMENT COMPRISING: A PLURALITY OF ROD MEMBERS EXTENDING RIGIDLY WITHIN SAID CHAMBER, SAID RODS BEING SPACED THROUGHOUT 